Rheostat.



N. WILKINSON.

RHEOSTAT.

APPLICATION FILED APR. 17, 1912 1,086,109. Patented Feb. 3, 1914.

2 SHBETSSHEET l.

WAX Waco 53mm 1/ 93K 5 qVAjuQ/vW/OM Mme/WW9 N. WILKINSON.

RHEOSTAT.

A'PPLIOATION FILED 11.17, 1912.

1,086,109, Patented Feb. 3, 1914.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFICE.

NATHAN WILKINSON, MILWAUKEE, WISCONSIN, ASSIGNOR, BY MESNE ASSIGN-MENTS, TO ALLIS-CHAIJMERS MANUFACTURING COMPANY,- A CORPORATION OFDELAWARE.

RHEOSTAT.

-of which the following is a full, clear, and

exact specification. m

This invention relates to rheostats, and more particularly to waterrheostats.

ater rhcostats have been made wherein the electrodes are both movableand stationary and the eifective resistance in the first type is variedby raising and lowering said movable electrodes out of and into waterwhile in the latter type the resistance is changed by varying the heightor amount of water with respect to such electrodes. In other words, withrespect to stationary electrode type of water rheostats,the effectiveresistance of such rheostats-is varied by causing more or less of ,theelectrodes to-be immersedby raising and lowering the level of th'ewater. Such rheostats are being employed more and more for startingmotors, such as induction motors. In starting such motors, and motors ofvarious types, comparatively little time is required to accelerate themotors from a position of rest to full speed. Often times it is necessaythat the original effective resistance be fairly high. In order toreduce this high resistance within a. comparatively short time, a

ump of comparatively high capacity will be necessary to pump the water.A motor of corresponding capacity will be necessary to operate the pump.The cost of such an equipment in many instances is quite high.

It is therefore the object of my invention provide a simple and compactwater rheostat adapted to meet all of the requirements of commercial opration, and one which can be operated at a minimum cost. This object isaccomplished by providing a water rheostat wherein the electrodes arestationary and are located in water at all times, the effectiveresistance of such rheostat being varied by raising and lowering aninsulated or insulating member or members which are interposed betweenor surround such electrodes.

The various novel features of my invention will be apparent from thedrawings and the description, and will be particularly set forth in theappended'elaims.

Specification of Letters Yatent.

Patented Feb. 3,1914.

- Application filed April 17, 1912. Serial No. 691,4 07.

The invention is illustrated in the accompanying sheets of drawings, inwhich- Figure l is a vertical sectional view of-mv water rheostat; Fig.2 is a sectional view of the same rheostat taken on the line 2-2 of Fig.1, looking in the direction indicated by the arrows;.Fig. 3 is avertical sectional view of a water rheosta't which is a modificationofthe one shown in Figs. 1 and 2; Fig. 4 is a horizontal sectional view ofthe rheostat shown in Fig. 8, the section being taken on the line 4-4 ofFig. 3, looking 'in the direction indicated by the arrows Fig. 5

is a diagram of connections showing the.

rheostat illustrated in Figsfl and'2 as connected in the secondarycircuit of arr-induction motor; and, Fig. (3 is a diagram of connectionsshowing the rheostat illustrated in Figs. 3 and 4 connected in thesecondary circuit of an induction motor.

This rheostat i ncludesa receptacle or tank 10 containing a fluid 11,preferably water, the height of which may be seen by observingtliedndicator 9 secured to the upper part of said receptacle. Thisreceptacle is provided with a cover 12 normally retained closed by anysuitable means, such as by a bolt and nut 13, said cover being providedwith a central opening 1 1 through which a rod 15 is guided. Secured tothe lower end of the rod 15 is an insulated or 1 lnsulating frame 16including a plurality of downwardly projecting members 17 which formbatlles, to be referred to hereinafter. Also extending through the cover12 are conductors .18, to the lower ends of which are secured conductingplates 19, and connected to these conducting plates 19 are groups ofelectrodes 20, 21, and 22. The conductors 18 also pass through the frame16, being insulated therefrom and insulated from the cover 12 bybushings 23 having collar portions 21 whi'di hold said bushings in afixed position relative to the cover 12. The conductors 18 are providedwith C01- lars 25 to hold said electrodes in a fixed position in thereceptacle 12. These electrodes are suspended from the cover 12 by theconductors 1 8, there being four such conductors in this particularcase, one conductor leading to each of the groups 20 and ofthe'electrodes and the other two leading to the electrodes 21. From anelectrical standpoint, one.conductor 18 would be sufiicient for thecentral group 21 of elecbetween electrodes develops heat at. thebottrodes, but two are used in this particular 1 case primarily tomechanically balance said middle group 21 of electrodes, the rod 15being located between said two conductors. An electrical balance is,however, obtained by providing the middle group of electrodes with twoconductors, and in some cases this may be desirable. 'F' ch of thegroups of electrodes is provided with electrodes of difterent lengthsfor the purpose of making the value of efi'ective resistance more marked1 under different conditions. These electrodes are interposed betweenthe battles 17, or groups of electrodes and the baiiies are spacedalternately with respect to each other.

The :bafiies as a unit may be raised and lowered relatively to theelectrodes by any suitable means. In this particular case, for the sakeof illustration, I have shown fluid pressure means for effecting thedesired result. Secured to the rod 15 is a piston 27 which is adaptcd tobe actuated in acylilr; der 28. In the position shown the piston andbaiiie plates are in their lowest positions. The piston may be forced tothe upper end or the cylinder by rotating the handle 29 in acounter-clockwise direction until the valve opening 30 registers withthe openings 31 of the supply and connecting pipes and respectively. Insuch position, fluid under pressure passes from pipe 32 hrough the valve30, pipe 33, and under the piston, gradually raising it and the battleplates to the desired position. The battle plates and the piston may belowered due to the weight of said part by rotating the handle 29 in aclockwise direction until the valve openings 30 and 3e registerrespectively with the openings 35 and 31 of the exhaust pipe 35 andconnecting pipe 33. By means or this valve and similar arrangements therheostat may be controlled from a remote point.

As shown, the rheostat is in full resistance position and it connectedin circuit with a motor for accelerating or regulating purposescurrentwould pass between the cen tral group. of electrodes 21 and theelectrodes 20 and 22 respectively and current would pass betweenelectrodes 20 and 22 through the tank 10 and through the water betweensaid tank and said electrodes 20 and 22. In this position the currentpassing tom of the baflle plates and electrodes. Therefore the, water atthe bottom portion of the battle plates and electrodes becomes heatedand rises between the baflie plates, escaping upwardly through the frame16, coming into contact with the cooling coil 37 having an inlet 38 andoutlet 39. Cold water is referably circulated through this cooling coil37 which may be supported in the tank 11 by brackets 10 having pins 41for separating the adjacent turns of the coil. As the heated water atthe bottom of the baffle plates rises, cold water rushes into its place.A natural circulation is thereby provided, maintaining the water in therheostat at the desired temperature. It is to be noted that theelectrodes are located near the bottom of the tank, the tops 01"- theelectrodes being below the middle of the tank. comparatively largevolume of water. is above mentioned, the bottom of the electrodes andbullies and thereupon rises to the top of the tank and out of contactwith any parts of the electrodes. In fact such heated water becomes farremoved from such electrodes. This means that cold water is beingcontinuously circulated to those parts of the electrodes from which heatis being conducted. In this way the water is kept at the lowest possibletemperature.

In order'to decrease the eiiective resistance of the rheostat', thebafiie plates are raised as unit by the fluid pressure means abovereferred to. These baiile plates may be gradually raised until the lowerends of said battle plates are raised beyond the upper portions of theelectrodes. In this position minimum resistance is offered to thecurrent passing from electrode to electrode; When it is desired to cutin resistance the balile plates can be lowered by their own weight bymoving the handlej 29 to the proper position to permit the fluid underthe piston 27 to exhaust. These bailie plates are preferably somewhatwider than the electrodes, as shown in Fig. 2, to increase the path ofcurrent which may pass around the baili'es between the various groups ofelectrodes, especially when the rheostat is in full resistance position.The. r.eceptacle 10 is provided with an inlet 4A and an outlet 45 sothat a fresh supply of water may be easily provided at any time.

Instead oi having the electrodes in the form of plain plates; as shownin Figs. '1. and 2, the electrodes may take the form of conductingcylinders 16, L7, and 48, as shown in the modification in Fig. 3. Inthis modification the baflies, which may be made of tile or any otherinsulating material, are also shown in cylindrical form, the variousbattles 49, 50, and 51 completely surrounding the groups e8, 17, and -16of electrodes. For mechanical purposes,each of the groups 16, 4:7, and18 of cylindrical electrodes is suspended from the cover 52 by twodiametrically opposite conductors 53, 53 and 53*, respectively, as showndiagrammatically in Fig. 6. An electrical balance is also obtained inthis way. In this instance the longest of the central group ofelectrodes is directly electrically connected to the tank 54, as shownin Fig. 3, so that current between the central group of electrodes -18the water is heated near a sence and outer group 46 may be conveyed moredirectly from one to the other. The efiec- 'tive resistance of thisrheostat is varied in precisely the same manner as described inconnected in the secondary. circuit of an induction motor of the woundrotor type. Its use, however, is not limited to this particularapplication, but such rheostat may be used with different types ofapparatus.

for various purposes.

There may be various modifications and arrangements other than thosehere shown and described, and it is my intention to cover adll suchmodifications and arrangements which do not depart from the spirit andscope of my invention, as set forth in the appended claims.

What I claim as newis:

1. In a rheostat, the combination of a receptacle containing a fluid,stationary electrodes in said fluid, and movable battles-interposedbetween said electrodes and displacing only their own Volume of liquidfor varying the effective resistance of said rheostat. v

2. In a rheostat, the combination of a re ceptacle containing a fluid,stationary electrodes in said fluid, and movable baffles permitting freecirculation of fiuidltherebetween and interposed between said electrodesfor varying the effective resistance of said rheostat.

3. In a rheostat, the combination of'a. re-

ceptaole containing. a fluid, groups of stationary' electrodes ofdifferent lengths within said receptacle, and movable means interposed.between said groups of electrodes for varying the efiective resistanceof said rheostat. v

4. In a rheostat, a receptacle having a cover and containing a liquid,stationary electrodes suspended from said cover and immersed in saidliquid, and movable barriers separating said electrodes for varying theefi'ective resistance of said rheostat, said barriers being openlyconnected as a unit to permit their free movement in said liquid.

5. In a rheostat, the combination of a receptacle containing a liquid,stationary electrodes supported in said receptacle, and movable bafilesinterposed between said electrodes and being freely movable in saidliquid as a unit for varying the effective resistance of said rheostat.

6. In a rheostat, the combination of a liquid containing tank, groups ofelectrodes within said tank, the electrodes of each group varying inlength, and movable means i is including a plurality of bafiies movableas a unit to vary the effective resistance of said rhcostat.

7. In a rheostat,thecombination of a receptacle containing a liquid,stationary electrodes in said liquid, and movable means surrounding saidelectrodes and displacing only its own volume ort=liquid for varying theeffective resistance of said rheostat.

8. In a rheostat, the combination ot a tank containing a liquid,stationary electrodes in said liquid, and a member surrounding one ofsaid electrodes adapted to be moved relatively thereto for, varying theeiiective resistance of said rheostat and to displace nly its ownvolumeof liquid in its movement. 9. In a rheostat, the combination of areceptacle containing a: liquid, stationary electrodes immersed in saidliquid, and movable baflies interposed between said electrodes andbetween some of said electrodes and said receptacle for varying the 'efiective resistance of-the rheostat, said baffies being freely 1novable inand displacing only their own volumeof said liquid.

10. In a rheostat, the combination of a tank containing a liquid,cylindrical eleotrodes in said liquid, and a member movable rheostatwithout substantially changing the level of said liquid.

11. In a rheostat, the combination oi a re ceptacle containing a liquid,a plurality of stationary cylindrical electrodes in .said liquid, and acylindrical nonconducting member having an opening in each end andmovable with respect to said electrode for varying the effectiveresistance of the rheostat.

12. In a rheostat, the combination of a liquid containing tank, groupsof stationary spaced and connected cylindrical electrodes, and aplurality of movable non-conducting cylindrical members interposed.between said groups of electrodes and being movable as a unit forvarying the effective resistance of said rheostat.

13. In a rheostat, the combination of a liquid containing tank, groupsof stationary spaced and connected cylindrical electrodes, a pluralityof movable non -conducting cylindrical members interposed between saidgroups of electrodes and being movable as a unit for varying theeffective resistance of said rheostat.

Il. In a rheostat, the combination of a receptacle containing a liquid,stationary electrodes 1n said liquid, one of said electrodes being. incontact with said tank, and

with respect to said cylindrical electrodes for varyingthe QiIGCtlVEresistance oi said fluid containing receptacle, a stationary electrodein said receptacle, and a movable member arranged concentrically withrespect to said electrode andhaving an opening in each end for varyingthe effective resistance of said tank.

16. In a rheostat, the combination of a receptacle containing a liquid,stationary concentrically arranged electrodes in said liquid, andconcentrically arranged members freely movable and displacing no morethan their own volume of said liquid for varying the effectiveresistance of said rheostat.

17. In a rheostat, the comhinatimi of a tank containing a liquid,stationary concentrically arranged electrodes in said liquid, andmovable concentrically arranged members surrounding said electrodes andbeing arranged alternately with respect to said electrodes for varyingthe efiective resistance of said rheostat Without substantially changingthe level of said liquid.

18. In a rheostat, the combination of a receptacle containing a liquid,stationary electrodes immersed in said liquid, and a movable bafile forvarying the effective resistance of said rheosta-t, said electrodesbeing located in the lower half of said receptacle so that liquid hea dat or near the electrodes may circulat 3 from said elec trodes to aremote part of the receptacle for cooling.

19. In a rheostat, the combination of a receptacle containing a liquid,stationary electrodes immersed in said liquid, a movable baffle forvarying the effective resistance of said rheostat, said electrodes beinglocated in the lower half of said receptacle so that liquid heated at ornear the clecfluid containing receptacle, electrodes thcrein, one ofsaid electrodes having a plurality of conductors connected thereto forelectrical balance purposes, and a member movable relatively to saidelectrodes for varying the eiiective resistance of said rheostat.

21. The combination in a receptacle con taining liquid, of electrodes, aplurality of battles freely movable as a unit between said electrodes,said baltles and said liquid acting to create a resistance path ofvariable length between said electrodes, and cooling means in saidreceptacle adapted to cool and circulate the liquid that has becomeheated between said electrodes.

22. In a rheostat, a receptacle containing fluid, electrodes, and abaille adapted to act as a barrier between said electrodes, said baflleand said electrodes being wholly immersed in said fluid in all currentcarrying positions of said parts.

23. In a rheostat, the combination of a receptacle containing a fluid,electrodes in said receptacle, and bafiles interposed between saidelectrodes, said baflles and said electrodes being relatively movablefor varying the effective resistance of said rheostat and permittingfree circulation of said fluid between said parts. Y Milwaukee, Wis.,April 3, 1912. In testimony whereof I aiiix my signature, in thepresence of two witnesses.

NATHAN WILKINSON. Witnesses:

CHAs. .L. BYRON, Ron. E. SToLL.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents 1 Washington, D. C.

